What’s Mine is Yours… Including My Microbes

Guest blog post from Jennifer Tsang, the PhD microbiologist behind The Microbial Menagerie and a frequent contributor to the American Society for Microbiology (ASM).
If you’re living with someone, you’re probably sharing the rent, switching off on chores, and binge watching some of your favorite shows together. But you’re also sharing something else without realizing it: microbes.

Our bodies are covered with a smorgasbord of bacteria. Despite the low moisture, high salinity, and constant turnover of our skin cells, at any given time you can find millions of microorganisms that inhabit each square centimeter of skin. We shed over one million biological particles every hour, dispersing them throughout our living spaces.

So, how do microbes from our skin affect those we live with? Are microbial communities from a certain body part more amenable to change than others? How do things like our gender and pet ownership affect our skin microbes?

Scientists from the University of Waterloo began to unravel these microbial mysteries in an article published last year, by identifying the microbes from ten sexually active cohabiting couples. They sequenced microbes from seventeen skin sites on each individual and compared the microbes identified between partners, revealing how cohabitation impacts an individual’s microbiome.

They found that cohabitation can significantly influence the skin microbiome, but not so much that the microbiomes of partners merged into one shared community. “You look like yourself more than you look like your partner,” says Ashley Ross, lead author of the study. Still, computer algorithms could predict cohabiting couples correctly 86 percent of the time.

Not unexpectedly, the palms and feet sampled from the couples contained the most diverse communities of microorganisms and were most similar between partners. This is likely because of our direct and frequent contact with the floor and other surfaces.

Which microbial communities did researchers find to be the most common between the sexes? The inner thigh and the eyelid.

Other factors such as biological sex and body location have more influence than cohabitation on our skin microbiome. Using only thigh microbiome samples, a computer algorithm could correctly determine if the sample came from a male or a female 100 percent of the time.

Of course, our skin microbiome is affected by more than just our biological sex and those we live with. Pets bring with them their own unique set of microbes, and the time we spend exploring the outdoors also exposes us to a range of different microbes. Despite the small number of participants in this study, the scientists found that couples that have pets and/or spend more time outdoors have more diverse skin microbiomes.

It’s currently unclear how microbes from your cohabiting partner or family influence your health. Studies like this one could help us learn more about how microorganisms have co-evolved with our skin and may inspire future lifestyle changes that promote health and well-being.

Jennifer Tsang is a microbiologist turned writer. She writes for her microbiology blog called The Microbial Menagerie and for the American Society for Microbiology.